The embodiments disclosed herein relate to eyewear that preserves natural therapeutic effects (i.e., possible physiological benefits) of sunlight while providing eye protection and visual performance and comfort.
Prior art eyewear has been designed to provide physical protection to the user and improve vision for a variety of uses. For example, ultra violet and shortwave blue/violet light can damage the eye. Protective lenses have been designed to block or significantly limit exposure to these parts of the light spectrum. Prior art eyewear has been designed with a variety of lens filtrations to reduce transmittance of these ranges of known harmful light through the lens of the eyewear, but may impair some of the natural therapeutic effects of sunlight. Prior art eyewear has also been developed to provide comfort and improved vision for sports, target recognition, color enhancement, driving, and computer viewing among other uses. Additionally, eyewear may also incorporate photo chromic and polarization lens treatments to reduce glare. Examples of prior art transmission curves for brown, green and neutral gray lenses are shown in FIGS. 1-3.
People have a circadian rhythm which defines a person's normal day/night body clock. Circadian rhythm is predominantly affected by light exposure. Hence, anything that affects exposure to light can potentially alter that person's normal day/night body clock. For example, the following can affect a person's exposure to light, namely, 1) being indoors without sufficient natural light levels during the day, 2) being exposed to too low of a range of sunlight, and 3) travel across multiple time zones. It can also be affected by wearing sunglasses.
A person's circadian rhythm can be visualized as a sinusoidal wave. There is a wavelength indicated by time between peak to peak or valley to valley. There is a phase which is indicated by the position of the peak or valley within a particular day/night time period. Also, there is an amplitude of the sinusoidal wave indicating the height or strength of the circadian rhythm. By modifying a person's exposure to light, the wavelength, phase and intensity of the person's circadian rhythm can be altered. For example, exposure to light in the evening can affect the phase of the circadian rhythm by delaying the onset of melatonin secretion (and sleep). Phase shift is the principle behind adapting to jet lag.
Accordingly, there is a need in the art for an improved eyewear.